External unit for intercom



FIG. 1 is a top plan view of the external unit for intercom showing my new design;

FIG. 2 is a bottom plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a right side elevational view thereof; and

FIG. 6 is a left side elevational view thereof. 

The ornamental design for an external unit for intercom, as shown and described. 